Hello!
You have to make a blueprint that makes the mesh or actor rotate to look at the target location or actor each tick like NukePie explained. The math part is luckily done by UE! 
Something like this should work:
If you are trying it in code:
//Calculates the lookat rotation from direction vector
FVector direction = FVector::ForwardVector;
FRotator lookAtRotator = FRotationMatrix::MakeFromX(direction).Rotator();
If you are trying to make a skeletal mesh look at a target (like aiming) You should take a look at this documentation: [Creating an Aim Offset | Unreal Engine Documentation][2]
I hope this helps!
Elias